The present invention is directed to integrated circuits and their processing for the manufacture of semiconductor devices. More particularly, the invention provides a method and structures for depositing one or more films of materials using atomic layer deposition under a precursor treatment. Merely by way of example, the invention has been applied to the manufacture of advanced integrated circuit devices, but it would be recognized that the invention has a much broader range of applicability.
Integrated circuits have evolved from a handful of interconnected devices fabricated on a single chip of silicon to millions of devices. Conventional integrated circuits provide performance and complexity far beyond what was originally imagined. In order to achieve improvements in complexity and circuit density (i.e., the number of devices capable of being packed onto a given chip area), the size of the smallest device feature, also known as the device “geometry”, has become smaller with each generation of integrated circuits.
Increasing circuit density has not only improved the complexity and performance of integrated circuits but has also provided lower cost parts to the consumer. An integrated circuit or chip fabrication facility can cost hundreds of millions, or even billions, of U.S. dollars. Each fabrication facility will have a certain throughput of wafers, and each wafer will have a certain number of integrated circuits on it. Therefore, by making the individual devices of an integrated circuit smaller, more devices may be fabricated on each wafer, thus increasing the output of the fabrication facility. Making devices smaller is very challenging, as each process used in integrated fabrication has a limit. That is to say, a given process typically only works down to a certain feature size, and then either the process or the device layout needs to be changed. Additionally, as devices require faster and faster designs, process limitations exist with certain conventional processes and materials.
An example of such a process is formation of films using chemical vapor deposition techniques. These chemical vapor deposition techniques, commonly called CVD, often use precursor gases that are introduced using a plasma environment. The gases often form layers of materials, including insulation, semiconductor, and conductor. Although widely used in the manufacturing of semiconductor devices, CVD techniques often lack good step coverage for smaller features. These smaller features are often less than about 0.2 μm and has an aspect ratio about 10, but can be others.
Accordingly, atomic layer deposition (ALD) techniques have been proposed. These techniques provide films will good step coverage over such smaller features. An example of ALD has been described by M. Ritala and M. Leskela, “Atomic Layer Deposition”, in Handbook of Thin Film Materials, H. S. Nalwa, ed., Vol. 1,103 (2002). Unfortunately, ALD techniques have certain limitations. For example, ALD techniques are often difficult to maintain without contamination problems. Contamination often leads to device failure and reliability issues. These and other limitations may be found throughout the present specification and more particularly below.
From the above, it is seen that an improved technique for processing semiconductor devices is desired.